Specific conduction system

Block of propagation may occur in the specific conduction system leading to bradyarrhythmia... 

The perfusion of the heart walls and specific conduction system... 

The myocardium and specific conduction system (SCS) are perfused by the right coronary artery (RCA), the left anterior descending coronary artery (LAD) and the circumflex coronary artery (LCX). Figure 1.1 shows the great correlation of coronary angiography and CMDCT in normal coronary tree and some pathologic cases. 

Due to the fact that K2TaF7 - KF is considered to be part of the TaF5 - KF binary system, while the K2TaF7 - KCI system is a component of the interconnected ternary system K+, Ta5+//F", Cl", the single-molecule conductivity and activation energy of the systems was calculated based on density and specific conductivity data [322, 324]. Molar conductivity (p) depends on the absolute temperature (T), according to the following exponential equation ... 

Table 52. Specific conductivity (y) of molten systems KF - K2TaFy and KCl -K2TaF7. Reproduced from [324], A. I. Agulyansky, P. T. Stangrit, V. I. Konstantinov, Zh. Prikl. Khim. 51 (1978) 2720, Copyright 1978, with permission of Nauka (Russian Academy of Sciences) publishing.

As in the case of solutions, the specific conductance, K, the equivalent conductance, a, and the molar conductance, am, are also distinguished for molten electrolytes. These are defined in the same manner as done for the case of solutions of electrolytes. It may, however, be pointed out that molten salts generally have much higher conductivities than equivalent aqueous systems. 

A plot of the spectroscopically computed maximum ionic concentrations [SD ions]m (sum of free ions and ion-pairs) at the end of the reactions (m denotes maximum values throughout this paper, the subscript 0 denotes initial values) against the final values of the specific conductivity Km. for the equivalent runs (Tables 1 and 2) gave a straight line through the origin, showing that virtually only free ions were present in our systems if there had been important quantities of ion-pairs, this plot would have been markedly curved. 

General definitions relating to action potentials are given in Section 9. This section deals specifically with action potentials within the cardiac pacemaker cells and conducting system. 

Alkyl fluoride boron trifluoride systems were first investigated by Olah et al. (1957). 1 1 Addition complexes were observed at low temperatures, and their specific conductivity was measured. The specific conductivity of the propyl and butyl fluoride boron trifluoride systems was found three orders of magnitude larger than those of the methyl- and ethyl-fluoride systems. The latter systems on heating dissociated into their starting materials, whereas the former gave polymer mixtures (Olah, unpublished). 

Although this model has been successful for interpretation of results in a variety of systems, recent studies indicate that it represents an oversimplification" For instance dilatometry, specific conductivity and differential scanning calorimetry results obtained on networks swollen by water can be better descrobed if s of water are assumed bound, interfacial and bulk... 

The increase in conductivity is due to increase in dissolved surfactant, and this increase continues until all the crystallites dissolve. The peak in specific conductance is attained when the microemulsion is formed and the specific conductance levels off. The plateau of Figure 6 is often referred to as a "percolation threshold" (] ) and is reached when there is a disordered interspersion capable of bicontinuous structures ( ). Further addition of methanol results in a lowering of conductivity explained by the solution eventually approaching the conductivity of methanol. This is the region of molecular dispersion. These conductivity curves are similar to those observed by Lagues and Santerey (13) on a system of water, cyclohexane, sodium dodecylsulfate and 1-pentanol. 

Figures 7, 8 and 9 are plots at 25 C of specific conductance and density versus volume fraction of methanol in 2/1 triolein/ surfactant systems which are 4/1 molar ratios of 2-octanol to bis(2-ethylhexyl) sodium sulfosuccinate, triethylammonium linoleate and tetradecyldimethylammonium linoleate, respectively. For each surfactant system, a maximum for specific conductance and a minimum for density was observed at the same volume fraction, but this volume fraction of methanol varied between the three surfactant systems. At volume fractions of methanol above these abrupt changes, each system exhibited translucence, and it appears that gel-like structures form. These data are consistent for microemulsion structures that are based largely on geometric considerations (16-18).

Figure 7. Plots at 298°K of specific conductance and density against volume fraction of methanol in a 2/1 triolein/ surfactant system which is a 4/1 molar ratio of 2-octanol to bis(2-ethylhexyl) sodium sulfosuccinate.

System and composition T (°C) Specific conductivity (ohm-1 cm-1) Conduction mechanism Reference... 

The term, arrhythmogenic substrate, became a matter of interest to many researchers. The arrhythmogenic substrate means the pathologic and anatomic preconditions for the initiation of tachyarrhythmias such as myocardial fibrosis, aneurysm, the border zone between normal and ischemic or infarcted tissue, scars, diffuse myocardial injury in cardiomyopathy or the chronic alterations induced by myocarditis, and furthermore, accessory pathways or variations in the specific cardiac conduction system. These anatomic or pathologic altera-... 

At the time that this survey of chemisorption bondlengths was undertaken, the database of molecular adsorption structures [139] was even more sparse, inadequate for any clear pattern to be established. More recently, we have returned to this problem through a detailed study of one specific chemisorption system, namely CO on Ni surfaces [142,143]. The objective was two-fold. First, by conducting PhD experimental structure determinations for different phases of CO on Ni(100) and Ni(lll) it was possible to obtain Ni—CO chemisorption bondlengths for 1-,... 

Lower Conductivity. The equivalent conductance of nonaqueous solutions a( infinite dilution is often comparable to that of aqueous systems, but it decreases with an increase in concentration more rapidly than the corresponding aqueous systems (the effect of the lower dielectric constant). Since the specific conductivity, K (that which determines the resistance between cathode and anode) is proportional to Ac, the equivalent conductance, the IR drop between the electrodes of a cell in which deposition from nonaqueous solutions is to lake place will be greater than that in aqueous solution (see Section 4.8.7). The electricity needed to deposit a given mass of metal is proportional to the total E between the electrodes, and this includes the IR between the electrodes, which is much greater in the nonaqueous than in the aqueous cases. Hence, nonaqueous deposition will be more costly in electricity (more kilowatt hours per unit of weight deposited) than a corresponding deposition in aqueous solution. The difference may be prohibitive. 

The Fuoss-Onsager-Skinner equation satisfactorily describes the electrolytic conductance of lithium bromide in acetone. Values of 198.1 0.9 Q l cm2 eq l and (3.3 0.1) X I03 are established for A0 and KA, respectively, at 25°C furthermore, a value of 2.53 A is obtained for the sum of the ionic radii ( ). When bromosuccinic acid is added to 10 5 N lithium bromide in acetone, there is a decrease in the specific conductance of lithium bromide rather than the increase that is observed at higher concentrations. As the concentration of bromosuccinic acid is increased, the values obtained for A0 and KA decrease, while those for a increase when the bromosuccinic acid and acetone are considered to constitute a mixed solvent. These results do not permit any simple explanation. When bromosuccinic acid and acetone are considered a mixed solvent, the Fuoss-Onsager-Skinner theory does not describe the system. 

If the system behaved ideally, the specific conductances should be additive. Figure 7 shows the specific conductance of the solution corrected (by subtraction) for the specific conductances of the acetone and lithium bromide for various fixed amounts of lithium bromide as a function of bromosuccinic acid concentration. Inasmuch as this should be equal to the equivalent conductance of bromosuccinic acid, if there were no interaction among the conducting species all four curves should coincide with the curve for no lithium bromide. Clearly, some type of interaction must occur. 

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